1. Field of the Invention
This invention relates to a tone control arrangement for use in sound reproducing instruments such as multi-channel audio amplifiers, record players, tape recorders, radio and television receivers, and more particularly to a novel tone control arrangement which can attain any desired tone control utilizing a variable d.c. control voltage.
2. Description of the Prior Art
Prior art tone control arrangements are generally arranged to control the frequency response of an audible sound signal to be reproduced by directly varying those frequency components of the sound signal which are to be cut off or passed by means of, e.g., a variable resistor included in a tone control circuit. However, the conventional tone control arrangements arranged directly to control those frequency components of the sound signal which are to be cut off or passed have the disadvantages that they have a tendency to be affected by surrounding noise signal components, particularly in the case where a relatively long signal transmission line such as a lead wire or a printed strip conductor is used to introduce an input audible sound signal to be directly frequency controlled into the tone control circuit, thereby lowering the signal-to-noise ratio of the reproduced sound. Furthermore, in a multi-channel audio amplifier system, they usually require separate tone adjusting means such as variable resistors for the respective channels.